Rotary pump or motor



March 1957 c. s. PRENDERGAST 2,786,421

ROTARY PUMP OR MOTOR Filed May 26, 1954 Inventor c/m R1 [5 660/7 PRLC/VMAQ/W Attornegv ROTARY PUMP R MOTOR Charles Scott Prendergast, Eashing, England, assignor of one-half to Hamilton Gordon, Elstead, England Application May 26, 1954, Serial No. 432,549

Claims priority, application Great Britain November 24, 1953 1 Claim. (Cl. 103-123) This invention relates to rotary pump and motors.

Hitherto an approximately straight line or uniform flow has only been attainable with a rotary pump or motor constructed with a series of phase displaced rotors and a corresponding number of stator chambers. The present invention enables the same result to be attained, for the first time so far as we are aware, with a rotary pump or rotor having only one rotor and one stator chamber, with considerable simplification of construction and at greatly reduced cost.

By way of example certain embodiments of rotary pump in accordance with the invention are illustrated on the accompanying drawings, and the following description of these embodiments will enable the invention to be better understood.

Figs. 1 to 3 show a pump in which the rotor presents an even number of lobes and the stator has four radially slidable vanes, Fig. 1 representing a longitudinal section in the plane I-I of Fig. 2, Fig. 2 representing a cross-section in the plane II-II of Fig. l, and Fig. 3 representing a longitudinal section in the plane III-III of Fig. 2; and,

Fig. 4 illustrates diagrammatically the manner of forming the rotor perimeter in each of the aforesaid pumps.

Throughout the several figures the same references denote the same or similar parts.

In the pump illustrated 1 is a shaft journalled in suitable bearings in an inlet casing 2 and in an outlet casing 3, which casings are rigidly secured to an intermediate stator 4 as by means of bolts 5 (omitted from the longitudinal sectional views for clearness). The three members 2, 3 and 4 totally enclose a rotor 6 which is keyed on the shaft 1 and is a running fit within the bore of the stator 4 and between the containing faces of the inlet casing 2 and the outlet casing 3.

The perimeter of the rotor is cam-shaped and the bore of the stator is circular to form between them a plurality of similar part-annular spaces corresponding in number to the number of cam lobes.

Four vanes 7 are free to slide in four equally spaced radial slots formed in the stator 4 opposite to one another, thereby affording complementary pumping chambers. These vanes, which are the same width as the rotor 6, are located axially by the inlet and outlet casings 2, 3. On opposite sides of each vane radial channels 4a and 4b formed in the stator respectively connect the pumping chambers enclosed between the stator bore and the rotor perimeter with an axial inlet duct 4c and with an outlet duct 4d also formed in the stator. Each inlet duct 40 (see Fig. 3) connects with an axial duct 20 formed in the inlet casing 2 and communicating with the inlet chamber 2b therein which has a screw-threaded inlet connector 2a. Similarly each outlet duct 4d connects with an axial duct 30 formed in the outlet casing 3 and communicating with the outlet chamber 3b therein which has a screw-threaded outlet connector 3a. The inlet chamber 2b is closed by a sleeve 9 which locates the bearing in nited States Patent() the inlet casing for the rotor shaft 1 and which contains a gland seal. The sleeve is retained by a keeper ring 10.

In the surface of each vane 7, at the side adjacent to the outlet ducts 4b, 4d, is a channel 7a whereby the opposed pumping chambers are freely connected to the outer ends of both vanes.

The rotor 6 presents an even number (six) of equidistant lobes, the maximum radius of each lobe being slightly less than the radius of the circular bore of the stator to allow for running clearance. The parts of the perimeter of the rotor situated half-way between every two adjacent lobes are also concentric with the axis of the rotor and have radii which are less than the maximum radii by a pre-determined amount. The perimeter of the rotor provides a smooth and unbroken contour. The portions of the rotor perimeter lying between adjacent parts of maximum and minimum radii are so formed that each of the four sliding vanes 6, in passing from a part of minor radius to the adjacent part of major radius, must move in its guide with a constant or other suitable rate of radial acceleration until it reaches midway between the aforesaid parts and then moves with a similar rate of radial deceleration until it reaches the part of major radius; in passing from the part of major radius to the next part of minor radius the vane must again move in its radial guide at reciprocal rates of acceleration and deceleration. Accordingly, the individual flow variations of the complementary pumping chambers are mutually compensating, so that the two combined displacements from the chambers produced by the rotation of the single rotor 1 result in a straight line flow.

The relationship between the number of vanes and the number of lobes on the rotor is such that when two diametrically opposed vanes are in contact with parts of the rotor perimeter of maximum radii, the other two vanes are in contact with parts of minimum radii. In this example the vanes 7 are constrained to maintain contact with the rotor perimeter by means of compression springs 13. These springs are housed in retaining screws 14, which are threaded radially into the stator from its external periphery. Inlet and outlet channels are formed in the stator on either side of each vane and connect to the pumping chambers as previously described. The channels 7a formed in the faces of the vanes at the sides thereof adjacent to the outlet channels connect the outlets from the pumping chambers freely to the spaces at the outer ends of the vanes.

Thus, this construction also affords complementary pumping chambers the individual flow variations of which are mutually compensating so that the combined displacements from the pumping chambers produced by the rotation of the single rotor will result in a straight line flow. Moreover, equal and opposite areas of the rotor perimeter are always under constant hydraulic pressure so preventing the bearings being subjected to internal loading.

The manner of forming the perimeter of the rotor in each of the pumps described is clearly illustrated by Fig. 4. A represents the angular lengths of the portions of the rotor perimeter of major and minor radii, B represents the angular length of portion of the perimeter of varying radii,

represents those portions of the rotor perimeter in which radial acceleration and deceleration of the abutments occurs; r represents the minimum radii of the rotor and R represents the maximum radii of the rotor;

represents the radius of the rotor at a point midway between each part ofv major radius and the, adjacent part of minor radius.

While I have described my invention in one of its preferred embodiments; Frealize thatfmodifications maybe made, and; I. desire that' it;be understood tharno limitationsfupon lily-invention are intended other than may be imposedvby the scope'of. the appended claim.

I claim: i

A rotary pump or motor comprising av single rotor member and a single stator member having co-acting perimetrical surfaces, thetrotor membenbeing cam-shaped to present an even number. of. equally spaced lobes of at least six in number and the statoribeing substantially circular to form between them a plurality of similar partannular fluid spaces, an even number. of equally spaced vanes of at leastfour in number mounted for radial iovement in the circularly profiled stator andyieldingly urged into contact withithe cam-shaped surface of the rotor, said vanes being angularly. disposed to aiford complementary displacement chambers, the individual .fiovv variations of which as'tlie rotor rotates are mutually compensating so that the total displacement approximates 'a straight line .fiovv, andlfluidI inlet and discharge connections for said chambers situated on opposite sides of each of the vanes, the cam-shaped rotor. having equi;angular way pointto said adjacent arc.

Batman Qit9 2 h l o hisratant UNITED$TATES A ENTS 678,338 Harger July 9, 1901 1,280,601 Weidenbach Oct. 1, 1918 1,348,103 George .1; July 27, 1920 2,013,397 Balsiger Sept. 3, 1935 2,191,172 Lisovvski Feb. 20, 1940 2,221,308 Dist'Shert'Q; Nov. 12,1940 2,232,951 Feb. 25, 1941 2,4 52;4 67 k O c tf26, 1948 v 22,492,687 Dali Dec. 27,1949 12,501,947 Johnson Mar. 28, 1950 2,609,754 Pie'nder'gas't et' a1. 'Spt. 9, 1952 2,622,538 Vihce nt'ZLLQL Dec. 23, 1952 

